I am preparing my examination on next week.I face a challenge question on the textbook but it does not provide any answers.Can someone help me? Two questions distribute 10 marks for each. How can I answer point by point to get all the marks in this questions. Many thanks!

Consider this problem. A train carrying a tank of Chemical X has overturned on a railway bridge. The bridge runs over a river located in a national park (see Figure 1).

Figure 1 Chemical X spilled into the river and onto the riverbank on the right (grey arrow). The river is surrounded by four small fish ponds (A-D), as well as waterbird habitat (shaded areas). Fish pond B is connected to the river by underground water flow, and the waterbird habitat on the right riverbank includes fish pond D. There are two fish species in the area, one that lives in the river, and one that lives in the fish ponds.

You know that Chemical X is a chlorinated, lipophilic pesticide. You also know that the waterbirds in the area consume primarily fish.

(a) What do you think will be the most likely distribution of Chemical X in this environment? Justify your answer with reasons. 10 Marks

(b) With reference to the diagram above, which habitats and which living organisms do you think would be most at risk? Justify your answer. 10 Marks

Since when go bridges above river? I thought the bridges usually just cross the river. And since when are railways in national parks?

Anyway, pond A should be OK, pond B will be probably contaminated due to the connection. The contamination of ponds C and D is questionable with C having higher chance to be contaminated. All the birds will be probably contaminated.

Try to learn the concepts behind the question rather than just begging someone to answer the question for you.

The question correctly asked for the "most affected". The information offers the focus of contamination, the initial vector for spread (water flow) and that the pesticide is lipophilic - has an affinitiy for lipid/fat thereby probably persistent and accumulative. Lipophilic in this context does not necessarily mean water insluble so, with this apparently high water table and bioaccumulation, you'll likely find the pesticide generally distributed in wildlife. I'm not with Jack that any of the bodies of water are going to be "ok" but do agree with D being most immediately contaminated followed by C, B and less so A.

No matter what illustration you put in just to describe your point it is pretty obvious that chemical spillage, especially if it’s hazardous, is harmful in our ecology. From the illustration attached, since the spill is heading the river, the chemical will be spread quickly. Water was flowing from here to the pond so the living will die and waterbirds that consume it will be affected too. It’s just a matter of cycle when it started.

"the living wil die " I'd not dramatize the effect. We dont know the toxicity of this "pesticide" or it's solubility - both of which will be important to understanding acute and chronic affect. We do know it's "lipophilic" so can expect bioconcentration. The ecology is not "ours" - it is a dynamic.